Metal ring and manufacturing method for metal ring

Abstract

A metal ring of a transmission belt in a belt-type continuously variable transmission. A first nitrided layer formed in a main surface of the metal ring, and a second nitrided layer formed in an end surface of the metal ring are included. A thickness of the second nitrided layer is smaller than a thickness of the first nitrided layer, and surface hardness of the end surface is higher than surface hardness of the main surface. Even though the second nitrided layer in the end part is thin, the surface hardness of the end surface is high. Therefore, it is possible to restrain fatigue fracture starting from an end part, and it is also possible to restrain deterioration of abrasion resistance of the end surface.

Description

INCORPORATION BY REFERENCE[0001]The disclosure of Japanese Patent Application No. 2015-077984 filed on Apr. 6, 2015 including the specification, drawings and abstract is incorporated herein by reference in its entirety.BACKGROUND[0002]1. Field[0003]The disclosure relates to a metal ring and a manufacturing method for the metal ring, especially to a metal ring in a transmission belt of a belt-type continuously variable transmission, and a manufacturing method for the metal ring.[0004]2. Description of Related Art[0005]A steel belt-type continuously variable transmission (CVT), in which an input side pulley and an output side pulley are connected to each other by a steel-made transmission belt, is used in an automobile and so on. A transmission belt in the steel belt-type CVT has a structure in which a number of elements are lined up without space between them and attached to a metal ring laminate that is made from a plurality of thin-sheet metal rings laminated in a nested state. Ten...

AI Technical Summary

Benefits of technology

The patent describes a metal ring with a thin layer of nitrided material on the end surface that prevents fatigue fracture and maintains abrasion resistance. The metal ring is made of a special steel called maraging steel that contains nitrogen-affinitive metal, such as Cr. The method allows for easy and cost-effective manufacturing by using a process that involves aging treatment and nitriding. Overall, the metal ring has improved fatigue fracture resistance and abrasion resistance, making it ideal for use in various applications such as industrial equipment and medical devices.

Problems solved by technology

When thicknesses of the nitrided layers in the end parts become large, residual tensile stress in non-nitrided parts on inner sides of the nitrided layers of the end parts becomes large, and there is thus a possibility that fatigue fracture starting from the end parts could happen easily.

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